1. Field of the Invention
This invention relates to a photosensitive resin composition of a negative type, and more particularly to a photosensitive resin composition that enables formation of a thick film with a high sensitivity and also exhibits a superior developability in an aqueous alkali solution. This also relates to a process for producing a polyimide pattern by the use of such a composition.
2. Description of the Prior Art
As photosensitive materials having thermal resistance, those comprising a polyamic acid and a dichromate (Japanese Patent Publication (kokoku) No. 49-17374 corresponding to U.S. Pat. No. 3,623,870), those formed by ester linkage of a carboxyl group of a polyamic acid with a group having a photosensitivity (Japanese Pre-examination Patent Publication (kokai) Nos. 49-11541 corresponding to U.S. Pat. No. 3,957,512 and No. 55-45746), those comprising a polyamic acid and an amine compound having a photosensitive group (Japanese Pre-examination Patent Publication (kokai) No. 54-145794 corresponding to U.S. Pat. No. 4,243,743), those formed by silyl ester linkage of a carboxyl group of a polyamic acid with a group having a photosensitivity (Japanese Pre-examination Patent Publication (kokai) No. 62-275129), etc. are proposed in the past.
These, however, make it necessary to use organic solvent developing solutions when patterns are formed, and have a problem of some influence on health due to organic solvents and a problem of the disposal of waste liquor.
To cope with such problems, those formed by amide linkage of a carboxyl group of a polyamic acid with a group having a photosensitivity (Japanese Pre-examination Patent Publication (kokai) Nos. 60-100143 corresponding to U.S. Pat. Nos. 4,515,887 and 2,157,845), positive type photosensitive resin compositions comprising a mixture of a polyimide resin having a phenolic group with an ester of naphthoquinonediazidosulfonic acid (Polymer Engineering and Science, July 1989, Vol. 29, 954), etc. are proposed as photosensitive materials making use of aqueous solution developing solutions.
These, however, have problems that they exhibit no sufficient sensitivity when films are formed and also take a long time for development.